This invention relates to a tool for the installation of items that require tensioning, and more particularly to a tool for the installation of fasteners such as cable ties.
Cable tie fasteners are commonly installed by wrapping their straps around groups of articles and threading the straps through locking heads. The installation further requires pulling on the free ends of the straps until the articles are securely bundled. The free end typically is then severed in the vicinity of the head when a specified level of tensioning has been reached. To achieve a suitable installation it is advantageous to employ a tool which grips and tensions the free end of the strap.
A wide variety of installation tools are available for effecting the above functions. These tools vary in complexity, and may include elaborate internal structures for controlling the level of tensioning, reducing the force required to achieve a given level of tension, and other purposes. The present tool, however, is of a simple efficient design, an approach which has become increasingly popular.
Such tools are typically inexpensive, durable and hence well suited to heavy duty applications with minimal risk of malfunction. A tool of simple, efficient design should provide facile manipulative control of tensioning. Prior art designs for heavy duty installation tools, however, are awkward in that typically they require moving the body of the tool relative to the object to be tensioned. Furthermore, such prior art tools often raise considerable difficulties in the installation of cable ties in relatively inaccessible locations. Another shortcoming is that tools designed for tensioning and severing thick, heavy duty ties have been unsuitable for thinner ties, principally as to the severing function.
U.S. Pat. Nos. 3,284,076 and 3,344,815, assigned to the Thomas & Betts Co., Raritan, N.J., disclose a strap tightening and cutting tool that is said to be of rugged, durable design. The tool is operated by squeezing a pivoting handle toward a grip portion at the rear, thereby drawing back a tension plate. The tension plate carries at the front a rotatably biased pawl and a flange for engaging a strap, and is forwardly biased by a spring between the handle and tool grip. The tool further includes an internal cutter assembly which is actuated at a given tensioning level. The design has the disadvantage of high probability of mechanical interference in confined areas. Furthermore, the use of a complex internal cutter mechanism makes the tool vulnerable to mechanical failure.
Accordingly, it is a principal object of the invention to provide an installation tool for tensioning cable ties and like objects having a simple, durable design. A related object of the invention is that such a tool include a small number of moving parts, and avoid delicate mechanisms. A further related object is reducing the risk of malfunction during the normal operation of the tool.
Another object of the invention is to achieve an efficient mechanical design which reduces user fatigue. Desirably, the tool should permit installation of cable ties and the like while maintaining the body of the tool stationary, to facilitate use.
A further object of the invention is the provision of an installation tool design which permits tensioning of cable ties in relatively inaccessible locations.
Still another object is the provision of a sever device in such a tool which does not require delicate mechanisms, yet allows the tensioning and severing of both heavy and light straps. A related object is the design of an easily adjustable yet durable sever mechanism.
Illustrative installation tools of the prior art are disclosed in U.S. Pat. Nos.: 2,175,478; 2,729,994; 2,882,934; 3,154,114; 3,168,119; 3,169,560 (U.S. Pat. No. Reissue 26,492); 3,173,456; 3,332,454; 3,433,275; 3,661,187; 3,712,346; 3,735,784; 3,752,199; 3,983,111; 3,993,109; and 4,064,918.